Musings on a Fully Mature Green Roof Market
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As regional horticultural knowledge increases plants like this Phemeranthus calycinus /syn. Talinum calycinum will be used to increase the nectar value on extensive green roofs. Providing a higher level of ecosystem services to the project. Photo: Edmund Snodgrass
Many children get the question from adults, “What do you want to be when you grow up?”
In that context, here are some thoughts about what the future of the green roof industry might look like in the hope that these evolving ideas can spur more discussion about the direction of our industry.
The Scale of the Green Roof Market Is Proportional to the Scale of the Need for Its Ecosystem Services
While impervious areas in many watersheds are increasing much faster than green infrastructure is being installed, a mature green roof market would lead to a better balance. In order to know that, there would need to be field studies of the effectiveness of various green roofs relative to stormwater capture – retention and detention. That way local jurisdictions could know how much green roofing is needed to be installed in order to keep up with impervious area increases.
The Chesapeake Bay Watershed for example, loses on average 100 acres of previous area each and every day. The current rate of green roof installation is woefully short of replacing that loss from a stormwater perspective, let alone other areas of ecological loss from that reduction of forests and meadows. A fully mature green roof industry would need to remediate the current impervious area losses, as well as keep up with annual losses. If roof drains could be connected to at-grade landscapes, there could be increased efficiencies gained in storm water treatment.
The Design Elements of Green Roofs, Especially the Plants Are Optimized to the Local Conditions
A mature green roof industry would support invertebrate and bird populations by carefully selecting plants for the species’ specific relationship and work in concert with landscapes on the ground. For example, a pawpaw tree is the larval source for the zebra swallowtail butterfly. That tree could be planted around the building and the green roof plants could be selected to provide the nectar and pollen for that butterfly when they reach their adult stage of life. In addition, roofs could have built-in niches for the butterfly to hang its chrysalis and depressions that might hold ephemeral water sources.
Additionally, there needs to be local, regional and national green roof jurisdictional co-ordination to protect migratory populations.
Plants are always going to be the most site-specific part of the assembly and as such their selection and care will always need local expertise. The notion of one plant palette for all designs in all regions, is a sign of horticultural immaturity in the market.
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There Are Funded Regional Green Roof Research Centers
In order to take full advantage of green roof infrastructure, appropriate local knowledge is critical. A mature market would see regional, longitudinal green roof research centers that would help specify the optimal design in terms of ecosystem services, low carbon substrates, and regionally appropriate plants. This work can be accomplished through the Regional Centers of Excellence, a relatively new program developed by Green Roofs for Healthy Cities.
The University of Melbourne at Burnley houses a green roof plant evaluation area. Just starting its 10th year it is providing long term real world and important local data on over 250 varieties. The roof has areas of different media depth and half is irrigated and half is not. The resulting knowledge is critical for any high performance green roof market. Photo: Edmund Snodgrass
There Are Viable Career Paths to Jobs in the Green Roof Industry
A true market has jobs, livable wages, multiple career paths and training apprenticeships for designers, installers, maintenance people and nurseries. The market needs to grow from its current size in order to have a more reliable career path for interested green roof participants
Green Roof Products Are Existing Inside an Overall Carbon Calculation of the Building
In order to be a mature green roof industry, the return on investment (ROI) on the green roof needs to be measured against the building’s carbon footprint, including green roof material production and transportation. These elements must have a long and stable life during both shipping and installation.
The industry needs to support public policy development which are derived from calculations that measure carbon, stormwater performance and other desired outcomes, at all levels of government. This would encourage and require local ordinances to meet stormwater, carbon and heat index goals. Coordination would be necessary to occur among the levels of government, research bodies and funding streams.
These ideas characterize what I envision as a mature green roof industry. While we have come a long way in the past two decades, we still have much further to go in order to realize the full performance potential of green roofs – social, ecological and economic performance.
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Edmund Snodgrass is the President of Emory Knoll Farms/Green Roof Plants. He has written and lectured on green roofs in North America and around the world. His book, Green Roof Plants: A Resource and Planting Guide (2006) is a seminal work for the green roof industry.
